Bloomberg Chairman Steps Down from Blackstone Board

Bloomberg L.P. Chairman Peter T. Grauer has stepped down from a board of Blackstone Group LP after the private-equity firm struck a deal to buy a majority stake in the financial-information and terminal business of Thomson Reuters Corp.

Mr. Grauer, a member of the board of directors of Blackstone Group Management LLC, the general partner of Blackstone Group, stepped down, effective immediately, because Bloomberg is a direct competitor of Reuters, according to a regulatory filing Friday. His resignation was not a legal requirement, but he felt "this was the appropriate step given the appearance and potential of a conflict," the filing said.

Following Mr. Grauer's departure, the size of the Blackstone board was reduced from 11 members to 10 members, according to the filing.

On Tuesday, Blackstone announced that a group led by the firm was buying a 55% stake in the financial and risk unit of Thomson Reuters for $17 billion. The deal, which is one of the largest in Blackstone's history, reflects the firm's focus on the value of data. The Thomson Reuters unit is a major supplier of data to Wall Street trading floors. The unit will become a separate privately held firm and Thomson Reuters will hold a 45% stake.